Berlin 2014 – scientific programme

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MO: Fachverband Molekülphysik

MO 19: Femtosecond Spectroscopy 2

MO 19.1: Talk

Thursday, March 20, 2014, 16:30–16:45, BEBEL HS213

Ultrafast emission quenching in perylene diimides by structure rearrangement induced electron transfer — •Patrick Kölle¹, Igor Pugliesi², Artur Nenov¹, Heinz Langhals¹, Eberhard Riedle², and Regina de Vivie-Riedle¹ — ¹LMU München, Department Chemie, München, Germany — ²LMU München, LS BioMolekulare Optik, München, Germany

Perylene dyes have attracted great interest for the design of intramolecular energy and charge transfer systems. The influence of substitution of two fluorescent perylene diimides on the ultrafast intramolecular dynamics leading to efficient fluorescence quenching are investigated by transient spectroscopy and quantum chemical calculations. The fluorescent systems show no dynamics in the sub-nanosecond time region. For the first, the amino-functionalized molecule the stimulated emission signal decays rapidly on a sub-picosecond timescale, while the excited state absorption decreases with a time constant of several picoseconds. The theoretical analysis assigns the fast decay of the emission to a charge transfer from the amino substitutient to the perylene diimide chromophore. Experiments and theoretical PCM calculations in different solvents demonstrate that the dynamics of this fluorescence quenching correlate with the solvation time. For the second, the phenyl-functionalized perylene diimide a similar charge transfer emission quenching mechanism is observed. An efficient and fast fluorescence quenching still occurs but in comparison with the amino-functionalized molecule the lifetime of the charge separation is increased by more than a factor of ten.